Might I suggest that you take a slightly different approach?

Daisy chain the D1500s off the feeds to the front L and R. Tell the processor there is no sub. Set the fronts to full range (i.e. Large DSP). Set the subs to the position for use with DSP33s.

That way you get the benefit of two subs, you avoid the problem of the 568v2.5 apparently not supporting the set-up and you get closer to the recommended Meridian ideal of no subs but full-range speakers.

In the spirit of Spinaltap, I would like to confirm that I am not involved in the corrupt theft of a global sport.